Hitherto, glass cutters employing an elongated handle with a sharp cutting wheel at one end and optional ball hammer head at the opposite end have required the user to twist his wrist or arm in order to hold the handle in its proper position perpendicular to the glass surface and at the same time to apply the necessary downward pressure to cause the cutting wheel to scratch the glass. This maintenance of perpendicularity is essential for precision work, especially with fitting pieces of stained glass together. Where, as often occurs, the surface of the glass is undulating or the glass contains bubbles known as "seeds", the encountering thereof by the cutting wheel coupled with the simultaneous application of pressure while attempting to maintain the above-mentioned perpendicularity causes the user to push the cutter handle forward and thus to lose this perpendicularity. This results in the making of an imprecise, irregular and unsatisfactory scratch with the consequent production of irregularly cut glass pieces upon tapping the glass to separate the pieces.
Another prior form of glass cutter possessing the same disadvantage of difficulty in maintaining this perpendicularity and requiring an abnormal and fatiguing twist of the wrist or arm is provided with laterally-projecting arms located between the opposite ends of the handle. Still another prior form of glass cutter possesses a short handle with a ring pivoted thereto at the top thereof on a horizontal pivot axis, with an even worse tendency to "flop over" during scratching and lacking the hammer head to sever the glass into separate pieces on opposite sides of the scratch. The glass cutter of the present invention avoids all these prior disadvantages and maintains this perpendicularity during the application of the downward pressure by the index finger, the axis of which thus automatically coincides with the axis of the handle without necessitating the fatigue-causing twisting of the wrist or arm.